A radio apparatus that performs communication using a random access method, such as a wireless LAN, is required to keep awaiting a signal, since it is not known when the signal is transmitted. In general, a period of time for awaiting a signal is longer than a period of time for receiving a signal. In order to reduce power consumption of the whole radio apparatus, it is important to reduce power consumption during standby time.
As a method for reducing power consumption of the radio apparatus, for example, a method for improving a configuration of a synchronizing circuit in a digital demodulator is known (see Milos Krstic, et. al., “Optimized low-power synchronizer design for the IEEE 802.11a standard,” ICASSP 2003 pp. 333-336, for example).
However, the method described in the Non-Patent Document 1 has a problem such that power consumption of the analog demodulator in a receiving unit cannot be reduced while power consumption of the digital demodulator in the radio apparatus can be reduced.
The analog demodulator consumes as much power during standby time as when receiving a signal. Therefore, it is desired to reduce power consumption when the analog demodulator is in standby state to attain lower power consumption of the radio apparatus.
Accordingly, a radio apparatus capable of reducing power consumption during standby time is required.